EP 0417884 A2 19910320 - Methods of calibrating gas analyzers.
Title (en)
Methods of calibrating gas analyzers.
Title (de)
Verfahren zum Kalibrieren von Gasanalysegeräten.
Title (fr)
Méthodes de calibrage d'analyseurs de gaz.
Publication
Application
Priority
US 40604189 A 19890912
Abstract (en)
A method for calibrating a non-dispersive infrared gas analyzer especially adapted for measuring the concentrations of HC, CO and CO2 in a vehicle exhaust is described. The analyzer includes a sample chamber (42) for holding a sample gas, a radiation emitter (48) for directing a beam through the chamber and a detector (70) for indicating the amount of radiation absorbed. A plurality of filters each of which transmits radiation at an absorption band of a gas component to be detected are alternatingly positioned in the radiation path to produce a time-multiplexed signal having concentration information for all gases. A calibration assembly is provided which includes a plurality of calibration cells (142) selectively positionable in the radiation path in order to provide an internal calibration standard for two-point calibration of each gas channel. The cells contain one or more of the gas components to be measured at concentrations and pressures predetermined to compensate for the difference in optical path length between the calibration cells and the sample chamber A technique is provided for characterizing the calibration cells in situ after a conventional calibration using bottled calibration gas is performed. The time-multiplexed detector output is corrected for gain and offset errors "on-the-fly" without requiring demultiplexing through the use of an analog multiplier circuit. The correction factors are themselves determined without demultiplexing the detector output signal.
IPC 1-7
IPC 8 full level
G01N 21/27 (2006.01); G01N 21/35 (2006.01); G01N 21/31 (2006.01)
CPC (source: EP US)
G01N 21/274 (2013.01 - EP US); G01N 21/3504 (2013.01 - EP US); G01N 2021/3129 (2013.01 - EP US); G01N 2021/3174 (2013.01 - EP US); G01N 2201/1285 (2013.01 - EP US)
Designated contracting state (EPC)
CH DE FR GB IT LI NL
DOCDB simple family (publication)
EP 0417884 A2 19910320; EP 0417884 A3 19911127; CA 2018568 A1 19910312; JP H03107744 A 19910508; US 5060505 A 19911029
DOCDB simple family (application)
EP 90306360 A 19900612; CA 2018568 A 19900608; JP 13517990 A 19900524; US 40604189 A 19890912